I have a friend who asked me if I could make a hat for her dog...she had seen a picture online and showed it to me.
I came across [url=https://img3.etsystatic.com/000/0/6432449/il_fullxfull.259230987.jpg]this pattern [/url] on Etsy, and she said that was a good one. I purchased the pattern, knowing I'd have to alter it, as our dogs are large, not small dogs.
I found that while the pattern is a good starting place, I didn't really care for it to much. I had to increase and change it quite a bit to get the hat to fit my dog. It also doesn't call for decreases, so as you crochet in the round, you never get past the flat round shape. Once I chained space for the ears, I went around and skipped every other double crochet to help to bring it in and give it shape.
So, I find that it looks more like a beret, then a hat, but it's still adorable on her.